Particle charging apparatus for electrostatic filter



June 6, 1961 J. K. BRlxlUs ET AL 2,987,137

RARTICLR CHARGING APPARATUS FOR ELECTROSTATIC FILTER Filed Nov. 16, 1955 2 Sheets-Sheet 1 June 6, 1951 J, K, BRlxlUs ETAL 2,987,137

PARTICLE CHARGING APPARATUS FOR ELECTROSTATIC FILTER Filed Nov. 16, 1955 2 Sheets-Sheet 2 United States v.Patent 2,987,137 PARTICLE CHARGING APPARATUS FOR ELECTROSTATIC FILTER Jacob K. Brixius, Parma, and Herbert W. Trenbath, Jr., Shaker Heights, Ohio, assignors, by mesne assignments, to Rockwell-Standard Corporation, Coraopolis, Pa., a

corporation of Pennsylvania Filed Nov. 16, 1955, Ser. No. 547,258 Claims priority, application Great Britain Jan. 25, 1955 1 Claim. (Cl. 183-7) This invention relates to improvements in apparatusfor electrically charging particles entering at the upstream end of an electrostatic filter cell for retention on collecting electrodes in said cell downstream therefrom.

' One of the objects of the present invention is to provide in such an electrostatic cell, a foraminous grille at the upstream end thereof forming a wall off the cell at that location, the cell also having opposed side walls and being open on a side between said walls, the line wire ionizing electrodes being pant of a unitary structure comprising a rigid frame supporting spaced brackets between which the ne wire electrodes are held taut, there being ways provided in the cell and opening toward the open sidei of the cell so that the frame is slidable in the waysl to remove the unitary structure from the cell out through the open side thereof.

'Other objects of the present invention include the arrangement of the collecting electrodes as a set of parallel spaced charged plates alternating between the plates of a set of parallel spaced grounded plates, in which the laterally outer-most pair of the grounded plates form the opposed side walls of the electrostatic cell; the extension of two of the charged plates upstream from the rest of the set of charged plates and providing the ways for receiving the unitary ionizing structure at the upstream end of said charged plates; the arrangement wherein the grille at the upstream end of the cell is'ilat and the line wire electrodes are parallel and lie in a plane parallel to the grille at such a distance therefrom as to provide a charged eld between the ne wire electrodes and the grille; specilically, the spacing between the parallel wires in a preferred form is approximately 1.0 to 1.5 times the spacing between the plane of the wires and the frontgrille.

' In a modied form of the apparatus, a second set of parallel iine wire electrodes is mounted on the rigid frame spaced from the plane of the `above mentioned rst named fine wire electrodes and in a plane parallel thereto and downstream therefrom. Preferably, in this modiiied form, each of the wires of the second set of tine wire electrodes lies approximately mid-way between the extended planes of two of the grounded plates, and the grounded plates have upstream edges .parallel to the second set of fine wire electrodes so that ionization takes place between the fine wire electrodes of the second set and the upstream edges of the ground plates.

In the drawings,

FIG. 1 is a side elevational view of an electrostatic cell illustrating the invention, with part'broken away to more clearly show the construction;` Y

FIG. 2 is a front elevational view of the cell of FIG. 1 taken from the left-hand end thereof;

FIG. 3 is a -top plan View of the electrostatic cell of FIGS. 1 and 2; while FIG. 4 is a fragmental view taken from the same position as the view of FIG. 3 but illustrating a modified form of the invention.

While this invention might be applied to a number of different types of electrostatic lter cells, i-t is shown in accompanying drawings as applied to a filter of the type disclosed and claimed in the patent of C. W. Savitz, U.S. 2,639,781.

ICC...

Referring to FIGS. 1, 2 and 3, one of these lter cells comprises a set of grounded collector plates 10 which are parallel to each other, and of which the two laterally outermost plates 10a extend farther upstream than the rest of the set to the forward end of the cell where they are rigidly connected together by a foraminous grille 11. In the form shown, this grille is uniformly perforated with through holes 11a as illustrated in FIG. Z although other forms of grille could perform this function. One of the purposes of this-grille is to cause an even distribution of the air over the face of the filter cell as viewed in FIG 2 so that the flow of air per unit of cross-section of the filter cell is comparatively uniform. The set of grounded collector plates is held together by four rods 12 which extend between the parallel plates 10a and are held thereto by screws 13 which pass through the plates and into the ends of the rods.

Alternating between the grounded collector plates, there is a second set of charged plate electrodes 14 which are assembled together on a bar 15 centrally of each end the set of charged collector electrode plates in proper' position alternating between the grounded plates 10, at the upstream end of the cell, a pair of electrical insulators 17 is rigidly supported from the plates 10a and a bar' 18 extends rigidly between these insulators. A pair of brackets 19 rigidly connects the bar 18 to the bar 15 at this end of the cell. At the downstream end of the cell, insulators 20 are rigidly secured to the side plates 10a and a bar 21 is rigidly supported between these insulators. At the center of the cell, the bar is provided with a bracket 22 which is rigidly connected, and forms an electrical conductor, between the bar 21 and the bar 15 at that end of the cell. When the cell is in use, high voltage substantially direct current is supplied to the set of charged collector plates 14 by means of an electrical plug which enters the recess 22a in the bracket ZZ in the manner support top and bottom brackets 25 which are parallel to each other and extend generally in the direction of stream flow through the cell. Rigidly secured to the frame members 24 are angle shape members 24a which extend from top to bottom of the frame. The frame members 24, 24a are adapted to slide out of the open top of the cell, between the side Walls 10a, in ways provided between the flanges 26 on the end of the plate portions 15b and ears 27 struck up inwardly from the plate portions 15b so as to overlie the angle members 24a as clearly shown in FIGS. 1 and' 3. It results fromthis structure, that the unitary structure comprising the members 24, 24a and 25 is adapted to slide vertically out of the cell through the open top thereof. Preferably, detent members 28 are provided for holding each of the frame members 24 in the proper position with respect to the plate portions 15b. As shown in FIGS. 1 and 3, these detent members are in the form of buttons rigidly secured in leaf spring members 29 which are riveted at 30 to the plate portions 15b. These buttons 2S enter into suitable openings in the frame members 24 to hold the frame members in their proper position.

Patented- June 6, 1961 25. Referring to FIG. 3, the-tine wirev31 is secured inthe left-hand notch 32 in the lower bracket 2 5, then passes upwardly through the same notch in the upper bracket 25, then across the top of upper bracket' 25 as seen in full lines in FIG. 3,` then downwardly from theA top bracket to the bottom bracket in the second notch 32 from the left-hand end, then below the bottom bracket 25 as indicated in broken lines'in FIG. 3, then upwardly in the third notch, downwardly in the-fourth notch, etc.l At the right-hand end ofthe brackets ZS, the loose end*- of wire 31 is firmly secured in any suitable manner.

While the ne wire electrodes are shown running very tically, they might extend horizontally, that is crosswise of the collector plates. The spacing between the parallel ne wire electrodes 31 and the spacing s from the plane of the tine wire electrodesto the front grille 11 must be carefully arranged so that the field ofionization, as represented by the dot-dash lines in FIG. 3; will cover the entire upstream face of the filter cell. In apreferred arrangement of this invention wherein the distance s,

measured in inches from the line wire electrodes to grille, and E represents the kilovoltage of the electrical charge' on the tine wires, and k isa constant varying according to the line wire diameter, a preferred arrangement is represented by the formula s=k E1-5. Utilizing this formula, Where the charge is 10 kilovolts and k is 0.27 for a .004 inch diameter tine wire, the distance s is calculated to be 0.865 inch as the distance from Ithe tine' wires to the grille. There is a little latitude in the spacing between the parallel tine wires 31 and eihcient operation s obtained where the spacingv between parallel wires 31 is from 1.0 to 1.5l times the distances from thev wires to the grille. In one embodiment of the invention,

the distance between parallel Wires 31 was equal to L3 s.

Referring to FIG. 3i of the-draWings,--the dot-dash lines B indicate that thetine'wire` electrodes .31 lie approximately in the planes of the plates 10 as these planesare extended upstream. While this is a'rpreferredform, it is not absolutely necessary to' the operation of my invention.

Inthe modification shown'inrFIG. 4, all-of the partsareithe sameas thosefjust described, except for'lthefob' lowingchanges. Top and bottom brackets 33 similar to those described at 25, are rigidly" connected-together' by the'end frame members-24; The modilicationrconsists in supplying a second set'of ne wirefelectrodesfarranged parallel to' each other in'a plane parallel'to" the fronti grille and downstream from the rstnientioned .set of line wire electrodes. Readingfroni the top of FIG.'4

downwardly, the tine wire' electrodefis secured to the` bottom bracket 33 and comes upwardly through the first front notch, then across the top of the upper bracket 33 to the first notch 35, then downwardly to the bottom bracket 33, along the'under facerof thebottom bracket as indicated in` broken lines? in *y FIG. 4,.: then upwardly'.

through the second front notch, then across the top` of upperbracket 33 to the-second notch` 35, then down-r wardly, etc. workingY in this fashion clear across'the 4 brackets 33 ia single' length of tine' Wire with its free end lirmly lsecuredrin place. Preferably, the notches 35 are so arranged in this form of the invention that the' parallel wires 34 at the downstream edge of the brackets 33, lie in the planes indicated by the dot-dash lines C which are extensions of the charged plates 14 and midway between grounded plates 10. The upstream edges of the plates 10- are generally parallel to the tine wire electrodes 34 so`v that" ionization takes place' betweenl the ne wiresv 34 along thedot-dash lines D to the upstream edges ofthe" grounded plates 10. This gives a second complete coverage of the cross-section of the filter cell for ionization of particles as represented by the lines D of FIG. 4 along with the lieldl of ionization represented by the lines A of FIG` 4 similar to that described inA connection. with FIG. 3. Preferably alsointhe modicationeof FIG. 4,- therear' edgeof the brackets33 isa little closer tothe collector plate electrodcsfthan in thev case of thebrackets 25 of FIGS; l', 2 and 3.

Preferably, some means is provided for moving the cells into and out of holding frames as described in the` above mentioned Savitz patent and for this purpose aV handle 36 isi rigidly secured to the front grille 11.

Those skilled in this art will recognize that the electrical signs might be changed as between wires 31- and grillefll; For instancegjust inside of grille 11 a charged perforate surface couldbe provided, insulated froml the outside walls of the'cell. Then wires 31 could be connected to some' grounded portion of the' cell,l such as by suspension-V from the grounded set of collector plates.- What is claimedis: Apparatus fo'r electrically v,charging particles entering atn theupstream end-of` an electrostatic filter cell for retentionon collectingelectrodes in said cell downstream therefrom, said collecting electrodes consisting of a set of'parallel spaced charged plates alternating between the plates of a'set'of parallel spaced grounded plates, the laterally outermost pair of said grounded plates forming vertically' extending opposedy side walls for said cell, a

groundedforarninous grille at the upstream end of said cell forming a wall of said cell and connected with the laterally outermost'pair of said grounded plates, a uni-` taryfstructurecomprising a plurality of line Wire chargingy electrodes-held taut between spaced brackets and a rigid frameholding said bracketsspaced, the two outermost platesf'ofvsaid set off parallel spaced charged plates exe,

tendingsupstream from the rest of said set of charged plates, vertically extending1 ways" carried by the upstream ends of said two extending ycharged plates, and said frame beingslidable in` said waysto remove said unitary structure'ffr'omlsaid cell; `sad'cellbeing open` at the top oppositefsaid-untaryrstructure'for this purpose, said brackets andframeand ways-'being electrically lconductivev and said nected yman tweexfenaingenarged pates.

lferencescitedin the le of this` patent UNITED sTATEs PATENTS 2,486,520 Dah1ma'n' V Nov. 1, 1949*1 2,594,439 Lineal Apr; 1s, 195o assaggi" savitz May 26; 195s .2',6'9/'6g8a33` Ritiarlsn Dee..14, 19154x 2,780,305 Bonatz i e Feb. s,- 1957 

